In an unprecedented arrangement, West Kowloon station is divided into Hong Kong and Chinese immigration controls -- which means passengers can avoid an additional check when traveling in and out of Hong Kong.

The move has not been without controversy: part of the station is governed by Chinese authorities and patrolled by mainland police. Travelers from Hong Kong still need to have a valid Chinese visa or travel document to ride the train.

Tel Aviv-Jerusalem railway

The entrance area of the new Jerusalem Yitzhak Navon station, which currently shuttleBen Gurion airport by train.

Sarah Sendner/picture-alliance/dpa/AP Images

The Tel Aviv-Jerusalem railway -- Israel's first electric train line -- partially opened in September.

It currently links Ben Gurion Airport, 13 miles (20 kilometers) southeast of Tel Aviv, to the Jerusalem-Yitzhak Navon railway station. The journey takes around 20 minutes.

Once completed, the direct link between Tel Aviv and Jerusalem will reduce travel between the two to less than 30 minutes, with trains that run at a top speed of 100 miles (160 kilometers) per hour. It will be an alternative to the existing train route between Jerusalem and the ancient town of Jaffa, 6 kilometers from downtown Tel Aviv, which takes one hour and 40 minutes.

Originally slated to open in 2008, the project has been plagued by delays and no completion date has been announced. It's another controversial project: two sections of the line -- largely underground -- run through the West Bank, which is considered occupied Palestinian land by the international community.

Tangier-Casablanca high-speed line

Tangier is on the northwestern coast of Africa, where the Atlantic Ocean meets the Mediterranean Sea.

Zero Point Zero

Officially opened last month, this high-speed rail line will link the Moroccan cities of Tangier and Casablanca via the capital city of Rabat, and Kenitra in the north.

There are currently two direct trains daily from London to Amsterdam. There is no direct return, however, because the British and Dutch governments haven't yet reached an agreement regarding border control.

Eurostar is "planning to introduce a direct return once the governments have come to an agreement," which is expected to happen by the end of 2019, according to a spokesperson.

Baku-Tbilisi-Kars Railway

A carriage manufactured by Stadler for the new Azerbaijan-Turkey direct route.

Stadler

The Baku-Tbilisi-Kars Railway (BTK) actually opened in 2017. Connecting the capitals of Azerbaijan and Georgia with the ancient city of Kars in Turkey, the BTK stretches 513 miles (826 kilometers).

But in 2019, the railway will introduce a new route that will take passengers between Baku and the Turkish cities of Ankara and Istanbul -- the first direct train link between Azerbaijan and Turkey that doesn't require stops in Georgia, which shares borders with the two countries. Trains will have a maximum speed of 100 miles (160 kilometers) per hour, according to Stadler Rail Management, which is manufacturing the carriages.

While journey times on the routes have not been announced, the direct services will be a vast improvement on existing train lines. Currently, those traveling by train have to endure a 40-hour journey with multiple stopovers to get between the two capitals. Trains from Baku to Istanbul take three days.